CSF 2888 radiator drain petcock threads (1 Viewer)

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RWBeringer4x4

Mechanically Challenged
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hey all -

Hopefully this is a fairly easy question. I’m about to put in a CSF 2888 brass replacement radiator. I’m not a fan of the plastic drain plug wing nut.

It looks like the drain hole is threaded in the brass - but I can’t figure out what the threads are. It’s roughly 3/8 but the threads are larger (coarser) than 3/8 NPT. I’m guessing it’s a coarse M10 thread - maybe M10 1.5 or M10 1.25?

I’d like to build a tube extension like the OEM radiator had to get the drain point below the radiator cradle for easy access.

Has anyone been down this road? Worst case I’ll go buy an assortment of brass plugs and test fitting but metric plugs aren’t super available around here.
 
It seems like the place that you purchased the radiator from should be able to tell you.
 
Purchased from shifty eBay store - I suppose I could try to get in touch with CSF directly - but I’ve never had much luck getting answers from the bigger overseas outfits. Figured I’d try here first as I know others have run this same radiator.
 
A good radiator shop should be able to fab up something for you.
 
The plastic radiator plugs I've run across seem to have a thread all of their own. I've soldered in brass pipe bushings before when I've lost that silly plastic plug. Once when I had a radiator rodded out I had the shop put in an NPT "bung" as they called it. No big deal for them.
 
Here’s a BSPT chart. Does the plastic petcock or female side appear tapered?

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I just went down this road yesterday. Took my radiator out of my HJ45 to have leaks soldered. While out I went to NAPA and the owner was super nice and tried a bunch of brass plugs to replace the crappy plastic plug. Turned out this oil pan plug fits. I used an 8 mm O ring instead of the solid rubber ring for a good seal. 12 mm 125 thread.
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A good radiator shop should be able to fab up something for you.

Yeah I’d rather just fab it myself - seems pretty straightforward with the right plug/adapter to start with.

The issue is there is one radiator shop I know of near me - it’s an hour away, the owner is about 85 years old. I need to learn to do this stuff since all the shops seem to be drying up and blowing away.

The plastic radiator plugs I've run across seem to have a thread all of their own. I've soldered in brass pipe bushings before when I've lost that silly plastic plug. Once when I had a radiator rodded out I had the shop put in an NPT "bung" as they called it. No big deal for them.

Yeah - not a fan of the plastic wing nut, but this one does appear to have a legitimate thread (like three threads) but the rubber gasket at the base seems to do most of the sealing.

I just went down this road yesterday. Took my radiator out of my HJ45 to have leaks soldered. While out I went to NAPA and the owner was super nice and tried a bunch of brass plugs to replace the crappy plastic plug. Turned out this oil pan plug fits. I used an 8 mm O ring instead of the solid rubber ring for a good seal. 12 mm 125 thread. View attachment 1677458

So not a tapered thread? If not, I guess I could start with some bolts and see what threads. M12 seems wide for this hole - 3/8 (which is closer to M10, right?) seems closer. I wonder if CSF stuck to the stock M12 threads or went smaller.

Sounds like some trial and error in store!
 
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The radiator shop I went to was a Mom and Pop and Son place 100 yds from the railroad track. Pop took the radiator out of my car and immediately pressure tested in a vat of antifreeze. Found two stress cracks- one at top corner and one at base of lower outlet. Sanded areas. Soldered both while I watched and then pressure tested again. No leaks. Then he flushed from both directions in a concrete shower stall. Ask him if it needed to be cored and he said if it’s cooling don’t mess with it. Took about an hour and he charged me $25.00!!!
This is the sorry plastic plug and the replacement brass with O ring that fits in the well of the drain.
I’ve ordered a radiator plug from SOR and will switch out if fits.
 
Just for future reference - I made it back home and took some measurements.

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If I had to wager a guess, CSF is using M10x1.5 threads.

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It is VERY close to 3/8-16 SAE, but since I have 11 billion 3/8-16 bolts laying around I ran one in. It will make it a few thread turns but then start to bind - so it’s either M10x1.5 or it’s a tapered hole. I don’t have a coarse M10 - almost every M10 on the truck is 1.25 pitch, so I’ll need to find a bolt or plug to test it and confirm.
 
Pulled the drain plug on my copycat FJ40 radiator. I compared it to a M10x1.5 bolt. Sure seems to be a match. Trying to figure out a downtube type drain also.:confused:

Did find this thread
Radiator drain tube

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Yep, I spent last night scouring the web for any type of M10x1.5 to NPT adapter. There are a few M10x1.5 to 1/8NPT adapters out there, but the selection is slim. Something like this (although I'm sure they can be had for cheaper: Allstar Performance 50040 Adapter Fitting/NPT Female 10x1.5 mm to 1/8" - 2 pc | eBay)

From there, there are 1/8NPT petcocks (mostly for air compressor tanks). The fit of the drain hole in relation to the opening in the radiator cradle aren't well aligned. I suspect we may end up needing a down-tube (or we will need to expand the hole in the radiator cradle) to get the petcock below the radiator cradle anyway. Something like this could work, though I'm a bit concerned with the temperature range:

GRAINGER APPROVED Threaded Nipple,Low Lead Brass,1000 psi - 20XN64|706113-0240 - Grainger

Or this - for a down tube a bit shorter:

https://www.amazon.com/Merit-Brass-Fitting-Schedule-Seamless/dp/B00K0DBGZ0

At the end, however, what you end up with is a REALLY tiny hole by which to drain your entire radiator.

The hole in the bottom doesn't have a ton of "meat" to it, (particularly the gasket sealing surface) like the one discussed in the prior thread, so I'm hesitant to drill and tap it for something larger, but I may do a bit more research on that option after work. I guess if I tap for tapered NPT I can just use teflon tape as opposed to the rubber gasket.
 
Another option might be something like this. I wonder if a hose builder like Parker could make something?
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A diy option would be this fitting to a -4AN hose with a cap on the other end.
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I actually thought about doing the "poor man's" version of the flex hose. Just get a M10x1.5 hose barb, install it in the radiator with a length of rubber heater hose and a hose clamp, then shove a bolt in the end of the hose, and tighten with a hose clamp. then you could just remove the bolt to drain. Not pretty, but since the radiator is only going to be at about 15PSI, max, it doesn't need to take a lot of pressure.
 
The flex hose option might be a very good one, particularly if the drain plug doesn't line up well with the hole in the radiator cradle. You could "bend the hose out through the hole in the cradle. Plus - I still have a few inches of that -6AN hose you shipped me, @thebigredrocker, so the "hose" part is done - just need the fittings. Will take some measurements tonight and see if I'll run into the radiator mount if I go straight down from the drain hole. If I do, (and I suspect I will) I'll probably try to find a 90-degree or 45-degree fitting to mount at the radiator, then run the hose out and down sideways through the hole to the plug you referenced above. It would wind up being one expensive drain tube if I go that route, but should be pretty bombproof.
 
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Ok so here is what I came up with using -6AN fittings and adapters.

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I made it long with the intention of tucking it up against the radiator cradle with a hose clamp:

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The hope is this would keep it out of the way when not in use, and give me a nice long “dangle” to help aim it at a bucket when draining the radiator.

The issue is, it hangs below the frame JUST slightly - and creates a loop that could potentially catch a branch or something (if it got past the bumper and steering components).

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Is this a big enough issue to be of major concern? It’s not big deal to shorten the hose. I like it from a convenience perspective but I haven’t done a lot of off-roading - naturally if this were to catch something it’s threaded into a brass radiator, which means I could, potentially, rip out the whole bottom of the tank.

For those with more off-road experience than I have - would this loop be a deal breaker?
 
Nice!

One option would be to use a zip tie. Or instead of using a steel bolt to hold the clamp, use a plastic bolt.
 

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